The present invention relates to an aluminum alloy for electrical conductors which is easy to manufacture and which has good elongation characteristics.
In the past, soft copper wires were exclusively used for communication cable conductors, magnet wires, etc. However, aluminum has come to be used in partial substitution for them because of the exhaustion of copper resources and price fluctuations. For such aluminum, there is available aluminum of electric conductor grade (hereinafter to be referred to briefly as EC-Al), which has been in use for overhead transmission and distribution cables for some time. If this EC-Al is subjected to drawing work, it undergoes work hardening and its elongation decreases remarkably. With a cold working of about 90%, resulting in an elongation of 3% or less, its workability is also degraded remarkably. Furthermore, when it is used as a soft material, the EC-Al has at most a tensile strength of only 8-10 Kg/mm.sup.2 and has had a drawback in that its mechanical strength is low.
With respect to Al-Fe alloys relating to the present invention, there is, for example, the alloy disclosed in U.S. Pat. No. 3,827,917. According to that patent, heating is done at 500.degree. F. .about. 900.degree. F. (260.degree..about.428.degree. C.) in the intermediate process step after casting and working. This heating is done for the purpose of recovering electric conductivity by precipitating Fe in solid solution in the form of fine particles.
The present inventors have discovered there is a shortcoming in that although Fe in solid solution is precipitated in the form of fine particles and electric conductivity is recovered as mentioned in U.S. Pat. No. 3,827,919, if the temperature of the aforementioned heating in ingot form is as low as 499.degree. C. or lower, the elongation characteristics of the alloy in a highly worked-on condition in the cold working step, done after the hot working, are degraded just as in the case of EC-Al, resulting in poor workability.